A near-irresistible exercise in bravura absurdity, Darren Aronofsky's Black Swan is the most risible and riotous backstage movie since Showgirls. Not body but ballet horror, the film is propelled by Natalie Portman's game determination and near-excruciating anxiety as Nina, a dogged, delusional, mildly masochistic, possibly virginal, and severely repressed little ballerina plucked from the ensemble to dance the Swan Queen and, as customary, her evil twin in a new vision of Swan Lake concocted by the sleaziest ballet master to ever slime Lincoln Center (Vincent Cassel). Frequently heard to whimper that she just wants to be "perfect," Nina is one tense chick. But, really, who could blame her? The tremulous child is stalked and brutalized onstage and off-, as well as in her dreams. Aronofsky has a near-documentary fascination with the minutiae of physical training, but in the end, Black Swan is all about penetration, blood, and psychosis. Mind games multiply en route to Nina's inevitable swansong. Black Swan is a hoot, and compared to the ponderous pulp mysticism of The Fountain, Aronofsky's suffocatingly self-important attempt to out-kibitz the Kabbalah, it's surprisingly fluid. Despite (or perhaps thanks to) the shock cuts, zap hallucinations, off-kilter framing, moody chiaroscuro, and repetitive creepiness, Black Swan is something like a 100-minute swoon. The camera lurches, leaps, and pirouettes; in some scenes, it feels as if it's being tossed around the stage along with Portman. Kitsch this bombastic becomes something primal.